Identification & synonyms: The original description and figures of Platyprosapus platymelus and Dorcus marginalis (reproduced here) left no doubt that the taxa belong to the same species closelyallied to Serrognathus westermanni. Saunders (1854) stated that platymelus differs from westermanni “inthe head being more quadrate and less transverse , and also in the mandibles , which are nearly truncated ,and not curving downwards as in that species.” An examination in both external and genital characters ofmany specimens from southeastern China proved all specimens fitting Saunders’ description belong to a single species. The type locality of platymelus was not explicitly indicated, but was restricted to the Teadistrict in southeastern China, around the current provinces of Fujian and Zhejiang. Our study concludedthat all populations from Zhejiang, Fujian, Guangdong, Jiangxi, Anhui, Hubei, Hunan, Henan, and Guangxicannot be separated by external characters and should belong to the same subspecies. 

Dorcus obscurus was described on a female from Tea district, together with D. platymelus and D.marginalis. It was treated as a synonym of platymelus by Parry ( 1864 ) and this opinion was followed bymost of the later authors ( Arrow 1950, Benesh 1960, etc. ). Albers ( 1886 ) however pointed out that thedescription of obscurus did not agree with the original figure in striae of elytra and considered his newspecies, consentaneus as same as the original figure of obscurus. Indeed, the original figure of obscurus isa simple hand drawing of the small-sized female of platymelus with too weak striae to be drawn on thefigure; it is different from the larger normal female specimens of platymelus by having a different shape ofelytra, but such body-shape has been observed among our specimens of platymelus in small size (such as No.14-8 figured in plate 21); it differs from consentaneus in striae of elytra. On the other hand, the original figure of obscurus looks like a female of Dorcus vicinus, which was described by the same author in the same paper ( Saunders , 1854 ) , but does not agree with the latter in having a wider lobe of canthus outside ofeye and the larger lateral spines on metatibia. In our opinion , Dorcus obscurus is definitely a juniorsynonym of S. titanus platymelus, representing a small-sized female. 

Eurytrachelus titanus hangul was described on the unique male from Siaolou, western Sichuan. Etitan hymir was described on 5 males from Kwanhsien (now Guanxian, west of Chengdu), I male fromKinfuschan (now Jinfoshan, Chongqing), and 1 male and 2 females from Yunling(now north western Yunnan), with I male from Kwanhsien as “Typ” in sense of the current holotype concept. The uniqueholotype of hangul from Siaolou and the “Typ” of hymir were kept in SMTD and examined by photos as figured below. They came from very neighbouring areas in western Sichuan and differ a little in width of head, pronotum and mandibles, all of which fall into individual variations of ssp. platymelus. Specimensfrom Sichuan do not differ constantly from the specimens of ssp. platymelus from eastern and central China; males in form of hangul or hymir are frequently found among specimens from eastern China, andmales in form of typical platymelus are frequently found among specimens from western Sichuan too. The males from the same locality can vary considerably in length of the mandible, the position of major toothon the mandible, the number and size of teeth in serration range of the mandible, and the width of head; wefigure above two males collected by Mr. Y. He from the same locality in Hangzhou, eastern China withvery different mandibles. Thus it is more appropriate to treat hangul and hymir as synonyms of platymelus.